Not Applicable.
Not Applicable
1. Field of the Invention
This invention relates generally to automatic test equipment of the type that includes a tester that docks with a peripheral, such as a prober or handler, for testing integrated circuits. More particularly, this invention relates to devices and methods for attaching an interface board, such as a device interface board (DIB) to a peripheral or tester prior to docking.
2. Description of Related Art Including Information Disclosed Under 37 C.F.R. 1.97 and 1.98
Automatic test equipment (ATE) for testing integrated circuits includes two principle componentsxe2x80x94a tester and a peripheral. The tester includes electronic hardware and software for exercising devices under test (xe2x80x9cDUTsxe2x80x9d), to ensure that the devices work properly before they are shipped to customers. The peripheral includes mechanisms for automatically transferring DUTs to a test site, in rapid succession for testing by the tester, and for transferring the DUTs away from the test site once testing is complete. By operating together, the tester and the peripheral can test large numbers of devices very quickly.
At the interface between the tester and the peripheral lies a device interface board, or xe2x80x9cDIB.xe2x80x9d The DIB generally includes a printed circuit board, a stiffener, and electrical contacts for conveying signals between the tester, the printed circuit board, and the peripheral. In a normal testing configuration, a DIB is attached to either the peripheral or a portion of the tester called the xe2x80x9ctest head.xe2x80x9d A manipulator then physically positions the test head in alignment with the peripheral and causes the test head and peripheral to mechanically xe2x80x9cdock.xe2x80x9d The act of docking sandwiches the DIB between the test head and the peripheral and allows electrical signals to pass between the tester and DUTs for testing. The DIB electrically connects with the test head via a number of spring-loaded pins or push-on, blind mate connectors. The DIB electrically connects with the peripheral in different ways, depending on the type of peripheral.
Peripherals come in two basic typesxe2x80x94xe2x80x9cprobersxe2x80x9d and xe2x80x9chandlers.xe2x80x9d Probers convey unpackaged semiconductor wafers to a test site for testing, whereas handlers convey packaged devices. Most probers require the use of a xe2x80x9cprobe tower,xe2x80x9d an array of double-sided, spring-loaded pins, for extending electrical signals from contacts on the DIB to contacts within the body of the prober. Signals pass in series from the tester, to the DIB, to the probe tower, and then into the body of the prober, where they are conveyed to test points of devices under test via probe needles. Handlers do not require probe towers. Instead, a xe2x80x9csocketxe2x80x9d is directly attached to the DIB for receiving devices under test.
Different techniques have evolved for attaching DIBs prior to docking when using probers and handlers. When using probers, operators customarily attach the DIB to the test head. This convention has evolved in part because tester manufacturers generally regard the DIB as part of the tester. The DIB may include special-purpose hardware for supporting various tests, and is often designed by the tester manufacturer. When using handlers, however, operators generally attach the DIB to the handler before docking. Because handlers do not require probe towers, there is no requirement that spring-loaded pins to be compressed when attaching a DIB to a handler. In addition, handlers generally impose exceedingly tight mechanical tolerances on the position of the socket with respect to the handler. These tolerances are more easily met by attaching the DIB to the handler, where alignment can be precisely controlled, than by attaching it to the test head, where alignment can only be established through the relatively coarse process of docking.
A prior technique for attaching a DIB to a test head before docking employs a round threaded ring having an internal shoulder that surrounds and engages the DIB. An operator places the ring around the DIB and screws the ring into a complementarily threaded region on the surface of the test head. Screwing down the ring draws the DIB against the surface of the test head and compresses spring loaded pins between them. Lever arms extending radially outward from the perimeter of the ring allow an operator to produce enough torque to compress the contacts between the test head and the DIB by turning the ring only a fraction of a revolution.
A prior technique for attaching a DIB to a handler before docking employs screws positioned around the perimeter of the DIB. An operator places the DIB against a receiving surface of the handler in careful alignment, and turns the screws to fasten the DIB in place.
Recent advancements in tester design have dramatically increased the number of signals that testers can provide. More pins can thus be provided between the tester and DIB, and between the DIB and the peripheral. More force is needed to compress the greater number of pins. In the Tiger test system available from Teradyne, Inc., of Boston, Mass., attaching a DIB to a fully loaded tester requires nearly 5000 Newtons of force, as compared with approximately half this amount for the previous generation of testers. This force is too great to be managed conveniently and practically by the threaded ring approach described above.
Moreover, we have recognized a need for greater consistency in the way that DIBs are attached when using probers and handlers. Two different techniques for attaching DIBs means that testing facilities that use both probers and handlers must maintain two different sets of hardware and train their personnel in executing two different procedures.
What is needed, therefore, is a technique for attaching a DIB substantially the same way for both probers and handlers, which is fast, convenient, and capable of applying significant forces for compressing large numbers of spring-loaded pins.
With the foregoing background in mind, it is an object of the invention to enable a DIB to be attached prior to docking in substantially the same way for both probers and handlers.
It is another object of the invention to attach a DIB quickly and conveniently.
It is a further object of the invention to enable an operator to easily apply sufficient force to compress spring-loaded pins when attaching a DIB.
To achieve the foregoing objects, as well as other objectives and advantages, a to mechanism for attaching a DIB to a surface of a test head or peripheral includes first and second pulldown mechanisms attached to the surface and a substantially U-shaped actuator. Each of the first and second pulldown mechanisms includes a rotating member coupled to a connecting member via a translation interface or mechanism. The translation interface or mechanism converts rotation of the rotating member into vertical movement of the connecting member. The U-shaped actuator has first and second ends coupled to the rotating members of the first and second pulldown mechanisms. Swinging the U-shaped actuator through an arc rotates the rotating members of the first and second pulldown mechanisms, thereby causing the connecting members to move vertically.
In accordance with one embodiment of the invention, the DIB includes mating members for mating with the connecting members of the pulldown mechanisms. The mating members are disposed at locations of the DIB that allows them to engage the connecting members when the DIB is placed against the surface in a testing configuration. Once the mating members engage the connecting members, the U-shaped actuator can be swung through an arc to pull the DIB against the surface. Because the arc that the U-shaped actuator describes greatly exceeds the amount by which the DIB vertically moves, the mechanism imparts significant mechanical advantage for depressing large numbers of spring-loaded pins.
According to one variation, each mating member includes a spring-loaded latch for latching with the corresponding connecting member in response to the DIB being placed against the surface in the testing configuration. Once the DIB is latched to the surface, the DIB remains attached, even if an operator physically releases the DIB. The operator can then swing the U-shaped actuator to pull down the DIB, without having to simultaneously hold the DIB in place.
According to another variation, each mating member further includes a grasping member mechanically coupled to the spring-loaded latch and forming a handle for manually conveying the DIB to the peripheral. The handle can be rotated against a resisting force, for engaging the spring-loaded latch with the corresponding connecting member, or for disengaging the spring-loaded latch and thus freeing the interface board from the surface.